Improving fuel efficiency is becoming more and more important in modern automobiles. In this field there has been an age-old tradeoff between fuel efficiency and vehicle power. For example, a four cylinder engine placed within a vehicle typically provides a fuel efficient vehicle lacking substantial power, while a six or eight cylinder engine provides plenty of power, but not a vehicle that is overly fuel efficient.
One way in which this tradeoff has been resolved is to provide a vehicle in which some of the engine cylinders are used selectively (i.e. Cylinder De-activation). For example, in situations where maximum power is required the engine, which is constructed with eight cylinders or six cylinders depending on the engine type, utilizes all six or eight cylinders. However, when power requirements are small, the vehicle utilizes only three or four of the cylinders, and as a result fuel efficiency of the vehicle is increased significantly.
Several vehicle characteristics need to be addressed, however, when there is a change in the number of engine cylinders utilized. Aspects such as engine fuel distribution, heat distribution/dissipation and engine vibration patterns change. Vehicle noises also change, being different in each engine operating mode and also during a transition period when one mode changes to another mode.
What is desired is a way to minimize vehicle noise caused during a transition period when the number of engine cylinders being utilized is changed.